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<html lang="en">
<head>
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    <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, minimum-scale=1, user-scalable=no">
    <meta name="description" content="Dynamically rotate a model's wheels based on its velocity using node transformations.">
    <meta name="cesium-sandcastle-labels" content="Showcases">
    <title>Cesium Demo</title>
    <script type="text/javascript" src="../Sandcastle-header.js"></script>
    <script type="text/javascript" src="../../../Build/CesiumUnminified/Cesium.js" nomodule></script>
    <script type="module" src="../load-cesium-es6.js"></script>
</head>
<body class="sandcastle-loading" data-sandcastle-bucket="bucket-requirejs.html">
<style>
    @import url(../templates/bucket.css);
</style>
<div id="cesiumContainer" class="fullSize"></div>
<div id="loadingOverlay"><h1>Loading...</h1></div>
<div id="toolbar"></div>
<script id="cesium_sandcastle_script">
function startup(Cesium) {
    'use strict';
//Sandcastle_Begin
var viewer = new Cesium.Viewer('cesiumContainer', {
    shouldAnimate: true
});

//Make sure viewer is at the desired time.
var start = Cesium.JulianDate.fromDate(new Date(2018, 11, 12, 15));
var totalSeconds = 10;
var stop = Cesium.JulianDate.addSeconds(start, totalSeconds, new Cesium.JulianDate());
viewer.clock.startTime = start.clone();
viewer.clock.stopTime = stop.clone();
viewer.clock.currentTime = start.clone();
viewer.clock.clockRange = Cesium.ClockRange.LOOP_STOP;
viewer.timeline.zoomTo(start, stop);

// Create a path for our vehicle by lerping between two positions.
var position = new Cesium.SampledPositionProperty();
var startPosition = new Cesium.Cartesian3(-2379556.799372864, -4665528.205030263, 3628013.106599678);
var endPosition = new Cesium.Cartesian3(-2379603.7074103747, -4665623.48990283, 3627860.82704567);
// A velocity vector property will give us the entity's speed and direction at any given time.
var velocityVectorProperty = new Cesium.VelocityVectorProperty(position, false);
var velocityVector = new Cesium.Cartesian3();
// Store the wheel's rotation over time in a SampledProperty.
var wheelAngleProperty = new Cesium.SampledProperty(Number);
var wheelAngle = 0;

var numberOfSamples = 100;
for (var i = 0; i <= numberOfSamples; ++i) {
    var factor = (i / numberOfSamples);
    var time = Cesium.JulianDate.addSeconds(start, factor * totalSeconds, new Cesium.JulianDate());

    // Lerp using a non-linear factor so that the vehicle accelerates.
    var locationFactor = Math.pow(factor, 2);
    var location = Cesium.Cartesian3.lerp(startPosition, endPosition, locationFactor, new Cesium.Cartesian3());
    position.addSample(time, location);
    // Rotate the wheels based on how fast the vehicle is moving at each timestep.
    velocityVectorProperty.getValue(time, velocityVector);
    var metersPerSecond = Cesium.Cartesian3.magnitude(velocityVector);
    var wheelRadius = 0.52;//in meters.
    var circumference = Math.PI * wheelRadius * 2;
    var rotationsPerSecond = metersPerSecond / circumference;

    wheelAngle += ((Math.PI * 2 * totalSeconds) / numberOfSamples) * rotationsPerSecond;
    wheelAngleProperty.addSample(time, wheelAngle);
}

function updateSpeedLabel(time, result) {
    velocityVectorProperty.getValue(time, velocityVector);
    var metersPerSecond = Cesium.Cartesian3.magnitude(velocityVector);
    var kmPerHour = Math.round(metersPerSecond * 3.6);

    return kmPerHour + ' km/hr';
}

var rotationProperty = new Cesium.CallbackProperty(function(time, result) {
    return Cesium.Quaternion.fromAxisAngle(Cesium.Cartesian3.UNIT_X, wheelAngleProperty.getValue(time), result);
}, false);

var wheelTransformation = new Cesium.NodeTransformationProperty({
    rotation: rotationProperty
});

var nodeTransformations = {
    'Wheels': wheelTransformation,
    'Wheels_mid': wheelTransformation,
    'Wheels_rear': wheelTransformation
};

// Add our vehicle model.
var vehicleEntity = viewer.entities.add({
    position : position,
    orientation : new Cesium.VelocityOrientationProperty(position), // Automatically set the vehicle's orientation to the direction it's facing.
    model : {
        uri : '../../SampleData/models/GroundVehicle/GroundVehicle.glb',
        runAnimations : false,
        nodeTransformations : nodeTransformations
    },
    label : {
        text: new Cesium.CallbackProperty(updateSpeedLabel, false),
        font : '20px sans-serif',
        showBackground : true,
        distanceDisplayCondition : new Cesium.DistanceDisplayCondition(0.0, 100.0),
        eyeOffset : new Cesium.Cartesian3(0, 3.5, 0)
    }
});

viewer.trackedEntity = vehicleEntity;
vehicleEntity.viewFrom = new Cesium.Cartesian3(-10.0, 7.0, 4.0);
//Sandcastle_End
    Sandcastle.finishedLoading();
}
if (typeof Cesium !== 'undefined') {
    window.startupCalled = true;
    startup(Cesium);
}
</script>
</body>
</html>
